1. Field of the Invention
The invention pertains to a hermetic feedthrough seal, wherein an inner conductor is electrically insulated from an outer vessel. The invention can be used, for example, in a pressurized battery used in a spacecraft.
2. Description of the Prior Art
U.S. Pat. No. 3,109,055 is typical of prior art devices wherein the seal is achieved by applying a radially inward crimping force to deform an outer metallic boss and an inner dielectric. The present invention, on the other hand, applies a compressive force in a radially outward direction.
U.S. Pat. No. 3,678,178 applies an inward compressive force to achieve a terminal seal, by means of turning nuts. This results in an uneven compression of the inner dielectric as well as the disadvantages of prior art techniques referenced below under "Summary of the Invention". The present invention employs a radially outward compressive force.
U.S. Pat. No. 4,053,692 discloses a glass to metal seal for separating metal electrodes in a battery cell, wherein the glass is melted. This seal is not amenable to high pressure applications. The present invention, on the other hand, is suited for high pressure applications, and employs a dielectric which is not glass and is not melted.
U.S. Pat. No. 4,197,363 discloses a seal for a sodium sulfur battery but does not pertain to a pressurized battery. The function of the seal is to keep two liquid electrodes apart. The compressive force is applied inwardly, compressing a soft metal by a hard ceramic. In the present invention, on the other hand, the seal is able to withstand high pressures; the compressive force is radially outward; and the electrodes are metal.
Secondary references are: U.S. Pat. Nos. 2,957,041; 3,874,929; 4,061,841; and 4,166,158.